The objective of this grant is to participate in the Acute Leukemia Group B. The aim of the Group is: 1st, to screen the value of new chemotherapeutic agents in patients with malignant diseases of the blood; 2nd, to explore the clinical-pharmacology of the known effective drugs, namely, to find the optimal dose, frequency of administration, sequence of administration, combination of administration and route of administration. In the course of our research, we have exposed normal PHA stimulated lymphocytes to various folic acid derivatives and anti- metabolites, such as FUDR and MTX, and then measured the uptake of radioactive thymidine and radioactive deoxyuridine. Also, we have measured thymidylate synthetase and dihydrofolic acid reductase in these cells.